Systems and methods of direct pointing detection for interaction with a digital device

ABSTRACT

The presently disclosed subject matter includes a method of recognizing an aimed point on a plane. Images captured by one or more image sensor are processed for obtaining data obtaining data indicative of location of at least one pointing element in the viewing space and data indicative of at least one predefined user&#39;s body part in the viewing space; using the obtained data an aimed point on the plane is identified. In case it is determined that a predefined condition is met a predefined command as message is executed.

FIELD OF THE INVENTION

This invention relates to user interfaces and to devices including auser interface.

BACKGROUND

Attempts have been made to implement hand gesture recognition, usingoptical sensors for use in inputting commands to a device. Gesturerecognition requires identifying a body part, such as a hand, in each ofa plurality of imagers in a video stream.

For example, gesture-based systems have been known to identify handgestures in a video stream. The gesture is classified for determining aninput into a related electronic device. The received input can be usedfor controlling various aspects of the respective system.

SUMMARY OF THE INVENTION

According to one aspect of the presently disclosed subject matter thereis provide a method of recognizing an aimed point on a plane the methodcomprising: obtaining at least one image of a viewing space of an imagesensor;

processing the at least one image by at least one processor operativelyconnected to the image sensor and obtaining data indicative of locationof at least one pointing element in the viewing space; obtaining dataindicative of at least one predefined user's body part in the viewingspace; and determining by the at least one processor, a point or area onthe plane, using the data indicative of the location of the at least onepointing element and the data indicative of the location of at least onepredefined user's body part, thus yielding an aimed point on the plane;determining, while obtaining data indicative of location of at least onepointing element in the viewing space that a predefined condition ismet; and executing a predefined command and/or message associated withthe aimed point.

In some cases the method according to this aspect of the presentlydisclosed subject matter can optionally comprise one or more of thefollowing features, in any desired combination or permutation.

i. Wherein the method further comprises: displaying on the plane atleast one graphical element; identifying by the at least one processor agiven graphical element from the at least one graphical elementdisplayed on the plane, using data indicative of the location of theaimed point on the plane.

ii. wherein determining the aimed point on the plane further comprises:identifying the at least one predefined body parts of the user; the atleast one body part including at least one of: face of the user; andpredefined facial parts of the user; identifying the at least onepointing element; determining location of the at least one body partswithin the viewing space, thus yielding a first location; determining alocation of the at least one pointing element within the viewing space,thus yielding a second location; determining at least one viewing raycorrelated with the first location and the second location; anddetermining the aimed point as a point on the plane associated with theintersection of the at least one viewing ray with the plane.

iii. wherein the determining of the first location comprises:determining two dimensional location of the at least one body part;estimating distance of the at least one body parts from the plane; andwherein the determining of the second location comprises: determiningtwo dimensional location of the at least one pointing element; andestimating distance of pointing element from the first location.

iv. wherein the determining of the first location comprises: determiningtwo dimensional location of the at least one body part; estimatingdistance of the at least one body parts from the plane; and wherein thedetermining of the second location comprises: determining twodimensional location of the at least one pointing element; andestimating distance of pointing element from the plane.

v. wherein at least one of, the estimation of the distance of the atleast one predefined body part from the plane; and the estimation of thedistance of the pointing element from the first location, is performedusing data stored in a data-repository.

vi. wherein the estimation of the distance of the at least one bodyparts from the plane is performed using data indicative of the distancebetween two or more facial parts of the user.

vii. wherein the estimation of the distance of pointing element from thefirst location is performed using data with respect to at least one of:height of the user; estimated proportions of the user's body; estimateddistance of the user from the plane; and multiple distance values, eachdistance value representing recorded distance between at least onepointing element and a predefined body part of a respective user duringa pointing gesture.

viii. wherein at least one of, the determination of the first location;and the second location, is performed using information obtained by theimage sensor and a depth sensor.

ix. wherein a resolution of the depth sensor is less than the resolutionof the image sensor.

x. wherein the second location is determined as the location of thepointing element at point P′ in the viewing space where the pointingelement is closest to the plane during a pointing gesture.

xi. wherein the method further comprises determining the location of thepointing element at point P′ using location features extracted from themotion of the pointing element during the pointing gesture.

xii. Wherein the method further comprises a calibration processcomprises: displaying on the plane a calibration sequence comprises atleast one graphical elements; for each given graphical element:identifying the at least one pointing element in the viewing space;determining at least one viewing ray connecting the given graphicalelement, the at least one pointing element and the predefined body partof a user; determining a respective location of the at least one of: theat least one pointing element; and the predefined user's body part; andstoring the respective location in a data-repository in association withthe given graphical element.

xiii. wherein the calibration further comprises: generating acalibration map indicative of an association between a plurality oflocations on the plane and a respective distance of the pointing elementfrom the at least one predefined user's body part.

xiv. Wherein the method further comprises determining the aimed pointusing data in the calibration map.

xv. Wherein the method further comprises the calibration sequenceincludes at least one graphical element whose selection is required toswitch a device operatively connected to the at least one image sensorand the at least one processor, from standby mode to active mode and/orunlock the device.

xvi. Wherein the method further comprises determining the aimed point onthe plane using at least one of a first type of features; and a secondtype of features; wherein the first type of features include featureswith respect to the motion path of the pointing element during apointing gesture, and the second type of features include features withrespect to at least one candidate plane.

xvii. wherein the first type of features include a collection ofselected position data component of the pointing element during thepointing gesture, which comply with a predefined criterion; the methodfurther comprises: for each given position data component in thecollection of selected position data, determining a respective viewingray; the respective viewing ray extending from the location of the atleast one predefined user's body part, through the location of the atleast one pointing element, and intersecting the plane, thus yielding arespective candidate plane; wherein the location of the at least onepointing element corresponds to the given position data component;determining an overlapping area between the respective candidate planes;determining the aimed point using data indicative of the overlappingarea.

xviii. Wherein the method further comprises: displaying a pointingvisual effect on the plane; detecting a motion path of the pointingelement in the viewing space; altering at least one characteristic ofthe displayed pointing visual effect in correlation with the motion pathof the pointing element, thereby providing data indicative of thelocation of the aim point on the plane during the pointing gesture.

xix. wherein the altering of the at least one characteristic of thepointing visual effect includes at least one of: reducing the size ofthe pointing visual effect as the distance between the pointing elementand the plane is reduced; and increasing the size of the pointing visualeffect as the distance between the pointing element and the plane isincreased.

xx. wherein the pointing visual effect is displayed when a predefinedpointing visual effect condition is met.

xxi. wherein the predefined condition is that the pointing elementpoints at the given graphical element displayed on the display for atleast a predefined amount of time.

xxii. wherein the predefined condition is that the pointing element hasperformed a predefined gesture.

xxiii. Wherein the method further comprises: identifying a predefinedfirst gesture performed by the pointing element; identifying the givengraphical element responsive to the first gesture; identifying apredefined second gesture performed by the pointing element; andexecuting a command and/or message responsive to the second gesture;wherein the command and/or message is associated with the givengraphical element; and wherein the second gesture is identified before,during or after the first gesture.

xxiv. wherein the at least one predefined user's body parts are user'seyes.

xxv. wherein the plane is a display.

According to another aspect of the presently disclosed subject matterthere is provided a device, comprising: at least one image sensoroperatively connected to at least one processor; the at least one imagesensor is configured to obtain at least one image of a viewing space;the at least one processor is configured to: process the at least oneimage and obtain data indicative of location of at least one pointingelement in the viewing space; obtain data indicative of at least onepredefined user's body part in the viewing space; and determine by theat least one processor, a point or area on the plane, using the dataindicative of the location of the at least one pointing element and thedata indicative of the location of at least one predefined user's bodypart, thus yielding an aimed point on the plane; determine, whileobtaining data indicative of location of at least one pointing elementin the viewing space that a predefined condition is met; and execute apredefined command and/or message associated with the aimed point.

According to another aspect of the presently disclosed subject matterthere is provided a user interface operatively connectable to a devicefor enabling inputting commands to the device, comprising: at least oneimage sensor operatively connected to at least one processor; the atleast one image sensor is configured to obtain at least one image of aviewing space; the at least one processor is configured to: process theat least one image and obtain data indicative of location of at leastone pointing element in the viewing space; obtain data indicative of atleast one predefined user's body part in the viewing space; anddetermine by the at least one processor, a point or area on the plane,using the data indicative of the location of the at least one pointingelement and the data indicative of the location of at least onepredefined user's body part, thus yielding an aimed point on the plane;determine, while obtaining data indicative of location of at least onepointing element in the viewing space that a predefined condition ismet; and execute a predefined command and/or message associated with theaimed point.

According to another aspect of the presently disclosed subject matterthere is to provided a program storage device readable by machine,tangibly embodying a program of instructions executable by the machineto perform the method of recognizing an aimed point on a plane, themethod comprising: obtaining at least one image of a viewing space of animage sensor; processing the at least one image by at least oneprocessor operatively connected to the image sensor and obtaining dataindicative of location of at least one pointing element in the viewingspace; obtaining data indicative of at least one predefined user's bodypart in the viewing space; and determining by the at least oneprocessor, a point or area on the plane, using the data indicative ofthe location of the at least one pointing element and the dataindicative of the location of at least one predefined user's body part,thus yielding an aimed point on the plane; determining, while obtainingdata indicative of location of at least one pointing element in theviewing space that a predefined condition is met; and executing apredefined command and/or message associated with the aimed point.

According to another aspect of the presently disclosed subject matterthere is provided a computer program code containing instructions forcausing a processor to perform operations of a method of recognizing anaimed point on a plane, the operations comprising: obtaining at leastone image of a viewing space of an image sensor; processing the at leastone image by at least one processor operatively connected to the imagesensor and obtaining data indicative of location of at least onepointing element in the viewing space; obtaining data indicative of atleast one predefined user's body part in the viewing space; anddetermining by the at least one processor, a point or area on the plane,using the data indicative of the location of the at least one pointingelement and the data indicative of the location of at least onepredefined user's body part, thus yielding an aimed point on the plane;determining, while obtaining data indicative of location of at least onepointing element in the viewing space that a predefined condition ismet; and executing a predefined command and/or message associated withthe aimed point.

According to certain embodiments of the presently disclosed subjectmatter the computer program code is embodied on a computer readablemedium.

The device, user interface, program storage device and computer programcode according to the different aspects of the presently disclosedsubject matter mentioned above can optionally comprise one or more ofthe features (i-xxv) above, in any desired combination or permutationmutatis mutandis.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to understand the invention and to see how it may be carriedout in practice, embodiments will now be described, by way ofnon-limiting example only, with reference to the accompanying drawings,in which:

FIG. 1 shows a system in accordance with the presently disclosed subjectmatter;

FIG. 2a shows a functional block diagram schematically illustrating aprocessing unit in accordance with the presently disclosed subjectmatter;

FIG. 2b shows a functional block diagram schematically illustrating anexample of system 2 in accordance with the presently disclosed subjectmatter;

FIG. 3 is flowchart showing an example of operations carried out inaccordance with the presently disclosed subject matter;

FIG. 4 is a schematic illustration demonstrating a point P′ while a useris pointing towards the screen, in accordance with the presentlydisclosed subject matter;

FIG. 5 is a flowchart illustrating an example of operations fordetermining point P′ carried out in accordance with the presentlydisclosed subject matter.

FIG. 6a is a schematic illustration showing a top view of a userpointing towards a display, in accordance with the presently disclosedsubject matter;

FIG. 6b is a schematic illustration showing different extensions of apointing element generating a similar projection, in accordance with thepresently disclosed subject matter;

FIG. 7 is a flowchart illustrating an example of operations carried outduring a calibration process, in accordance with the presently disclosedsubject matter.

FIG. 8 is a schematic illustration demonstrating an example of acalibration process carried out in accordance with the presentlydisclosed subject matter;

FIG. 9 is a flowchart illustrating an example of operations carried outin accordance with the presently disclosed subject matter;

FIG. 10 is a schematic illustration showing three partially overlappingcandidate planes, in accordance with the presently disclosed subjectmatter;

FIG. 11 is another flowchart illustrating an example of operationscarried out in accordance with the presently disclosed subject matter;and

FIGS. 12a and 12b are schematic illustrations an example of changes incharacteristics of a pointing visual effect responsive to pointinggesture of a user, in accordance with the presently disclosed subjectmatter.

In the drawings and descriptions set forth, where it seems appropriate,identical reference numerals indicate those components that are commonto different embodiments or configurations.

DETAILED DESCRIPTION

Unless specifically stated otherwise, as apparent from the followingdiscussions, it is appreciated that throughout the specificationdiscussions utilizing terms such as “obtaining”, “processing”,“obtaining”, “determining”, “executing” or the like, include actionand/or processes of a computer that manipulate and/or transform datainto other data, said data represented as physical quantities, e.g. suchas electronic quantities, and/or said data representing the physicalobjects.

System 2 described herein comprises or is otherwise connected to acomputer. The term “computer” should be expansively construed to coverany kind of electronic device with data processing capabilities,including, by way of non-limiting example, a personal computer, aserver, a computing system, a communication device, or a processor. Theprocessor can be for, example, one or more of a general purposeprocessor, a DSP (digital signaling processor), or a GPU (graphicalprocessing unit), configured to run one or more software programs.Alternatively the processor may be dedicated hardware, anapplication-specific integrated circuit (ASIC). As yet anotheralternative, the processor 6 may be a combination of dedicated hardware,an application-specific integrated circuit (ASIC), and any one or moreof a general purpose processor, a DSP (digital signaling processor), anda GPU (graphical processing unit).

The operations in accordance with the teachings herein may be performedby a computer specially constructed for the desired purposes or by ageneral purpose computer specially configured for the desired purpose bya computer program stored in a computer readable storage medium.

The term image sensor as used herein should be broadly interpreted toinclude any image acquisition device including for example one or moreof: camera, light sensor, IR sensor, ultrasonic sensor, proximitysensor, CMOS image sensor, shortwave infrared (SWIR) image sensor, orreflectivity sensor,

“depth sensor”, any other module that generate a video, indicating thedistance of objects in the viewing space of the sensor. Sensor modulemay include but is not limited to time of flight sensor, IR gridprojection, stereoscopic technology, and analysis of change inelectromagnetic fields. A 2 dimensional (2D) image is an image obtainedby an image sensor indicating data of the objects in the viewing space(FOV) of the sensor projected on a two dimensional plane. A 3dimensional (3D) image is an image obtained by an image sensorindicating data of distances and locations of objects in the viewingspace (FOV) of the sensor projected on a two dimensional plane.

As used herein, the phrase “for example,” “such as”, “for instance” andvariants thereof describe non-limiting embodiments of the presentlydisclosed subject matter. Reference in the specification to “one case”,“some cases”, “other cases” or variants thereof means that a particularfeature, structure or characteristic described in connection with theembodiment(s) is included in at least one embodiment of the presentlydisclosed subject matter. Thus the appearance of the phrase “one case”,“some cases”, “other cases” or variants thereof does not necessarilyrefer to the same embodiment(s).

It is appreciated that certain features of the presently disclosedsubject matter, which are, for clarity, described in the context ofseparate embodiments, may also be provided in combination in a singleembodiment. Conversely, various features of the presently disclosedsubject matter, which are, for brevity, described in the context of asingle embodiment, may also be provided separately or in any suitablesub-combination.

In embodiments of the presently disclosed subject matter, fewer, moreand/or different stages than those shown in FIGS. 3, 5, 7, 8, and 11 maybe executed. In embodiments of the presently disclosed subject matterone or more stages illustrated in FIGS. 3, 5, 7, 8, and 11 may beexecuted in a different order and/or one or more groups of stages may beexecuted simultaneously. FIGS. 1 and 2 illustrate a general schematic ofthe system architecture in accordance with an embodiment of thepresently disclosed subject matter. The modules/components in FIGS. 1and 2 may be centralized in one location or be dispersed over more thanone location. In other embodiments of the presently disclosed subjectmatter, the system may comprise fewer, more, and/or differentmodules/components than those shown in FIGS. 1 and 2.

It should be noted that the term “criterion” (or “condition”) as usedherein should be expansively construed to include any compound criterion(or conditions), including, for example, several criteria (or condition)and/or their logical combinations.

Bearing the above in mind attention is now drawn to FIG. 1 showingsystem 2 for touch free operation of a device having a display inaccordance with the presently disclosed subject matter. System 2comprises a device 4 having a display 6. The term “device” as usedherein includes, but is not limited to, any one of: a personal computer(PC), an entertainment device, Set top Box, TV, and a mobile gamemachine, a mobile phone or tablet, e-reader, portable game console, aportable computer such as laptop or ultrabook, a personal computer (PC),All-in-One, TV, Set-Top Box, connected TV, display device, a homeappliance, communication device, air-conditioner, a docking station, agame machine, a digital camera, a watch, interactive surface, 3Ddisplay, an entertainment device, speakers, a Smart Home, a kitchenappliance, a media player or media system, a location based device; anda mobile game machine, a pico projector or an embedded projector, amedical device, a medical display device, a vehicle, an in-car/in-airInfotainment system, navigation system, a wearable device, an augmentreality enabled device, wearable goggles, a location based device, arobot, interactive digital signage, digital kiosk, vending machine, ATM.

The term “display” as used herein should be broadly interpreted toinclude any type of plane or surface on which images or other type ofvisual information is being displayed, including, but not limited to,any type of display (e.g. a CRT, Plasma, LCD, LED, OLED, 3D display,e-ink). The term “display” may be broadly intercepted to include aprojector and a plane or surface on which it project any kind of imagesor visual information. It should be noted that where the presentdiscussion refers to a “display” this should be considered as a mereexample and should be broadly interpreted to include any type of displayincluding a plane or surface, as described above. The terms “display”and “plane” are used herein interchangeably.

An image sensor system 8 is positioned adjacent to the device 4 andobtains images of a three-dimensional viewing space (otherwise known asfield of view) indicated by the broken lines 10. A user 12 is situatedin the viewing space and thus appears in images obtained by the imagesensor system 8. The output of the image sensor system 8 can be forexample a 2D (two dimensional) color or infrared (IR) video.Alternatively, the image sensor system 8 may be a depth video systemcomprising a 3D image sensor or two 2D stereoscopic image sensors. Theimage sensor system 8 may comprise a combination of some or all of theabove mentioned image sensor types.

Images obtained by the image sensor system 8 are input to a processingunit 12 which may be integral with the image sensor system or connectedto the image sensor system by a wired or wireless communication channel.The processing unit 12 is shown schematically in FIG. 2b . Theprocessing unit 12 includes a processor 15 and a memory 13 which can beused for storing images obtained by the image sensor system 8. Theprocessing unit 12 is configured to analyze images obtained by the imagesensor system 8 and to track one or more predefined pointing elements,which are being used by the user for interacting with the display.Pointing element can be for example, a fingertip 14 of a user 16situated in the viewing space of the image sensor system 8. In othercases the pointing element can be for example one or more hands of auser, a part of a hand, one or more fingers, one or more parts of afinger (one or more fingertips), or a hand held stylus. It is noted thatin the following discussion the term “fingertip” is occasionally used asan example of a pointing element. This is done by way of non-limitingexample only and should not be construed to limit the presentlydisclosed subject matter in any way.

According to the presently disclosed subject matter, processing unit 12is further configured to determine a point or area on the display 6towards which the fingertip 14 is pointing (otherwise referred to hereinas “aimed point”). The processing unit 12 can be configured to indicatethe icon on the display 6 towards which the fingertip 14 is pointing asdetermined by the processing unit.

Indication (feedback) of an icon being pointed at can be provided, forexample as a visual indication, an audio indication, a tactileindication, an ultrasonic indication, or a haptic indication. A visualindication may be, for example, in a form such as an icon displayed on adisplay, a change in an icon on a display, a change in color of an iconon a display, an indication light, an indicator moving on a display, adirectional vibration indication, or an air tactile indication. Theindication may be provided by an indicator moving on a display. Theindicator may appear on top of all other images or video appearing onthe display. The user's eye 22, the fingertip 14 and the selected iconon the display 6 are collinear, lying on a common viewing ray 24.

It should be noted that the term “icon” as used herein is used as onenon-limiting example of a graphical element which is displayed on thedisplay and can be selected by a user. Such graphical elements caninclude for example, in addition to icons, 2D and 3D graphical elements,objects and/or part of an object shown within a displayed image and/ormovie, text displayed on the display or within a displayed file, objectswithin an interactive game, a pixel or a collection of pixels and soforth.

Processing unit 12 is also configured to display on the display 6 one ormore selectable graphical elements (e.g. icons) 20. Four icons 20 a, 20b, 20 c, and 20 d are shown in FIG. 1. This is by way of example only,and any number of icons can be displayed on the display 6 at any time.Any one of the icons can be selected by the user 16 pointing with thepointing element 14 at the particular icon the user wishes to select.

The processing unit may be configured to identify a selection of an iconby the user based on a predefined criterion. For example, when the userpoints at the icon for a predefined period of time (e.g. a predefinednumber of seconds) processing unit determines a desire to select theicon. According to another example, the processing unit may beconfigured to identify a selection of an icon by the user when the userperforms a predefined motion towards the selected icon. For example themotion can be a tapping motion, which consists of a movement of thepointing element 14 towards the selected icon followed by a movement ofthe fingertip 14 away from the selected icon. System 2 can be furtherconfigured to generate a visual and/or audio feedback when pointing toan icon and when selecting one.

As exemplified in FIG. 1, it is not necessary that the pointing element14 contacts the display 6 while pointing or during the tapping motion.In the example illustrated with reference to FIG. 1, fingertip 14 ispointing towards the icon 20 b. Selection of icon 20 b is detected bythe processing unit in images of a video stream obtained by the imagesensor system 8. When the processing unit determines that a particularicon has been selected, a corresponding command and/or messageassociated with the selected icon is executed.

It should be noted that as used herein a command and/or messagementioned herein can be addressed to any type of destination including,but not limited to, one or more of: operating system, one or moreservices, one or more applications, one or more devices, one or moreremote applications, one or more remote services, or one or more remotedevices.

The presently disclosed subject matter may further comprisecommunicating with an external device or website responsive to selectionof a graphical element. The communication may comprise sending a messageto an application running on the external device, a service running onthe external device, an operating system running on the external device,a process running on the external device, one or more applicationsrunning on a processor of the external device, a software programrunning in the background of the external device, or to one or moreservices running on the external device. The method may further comprisesending a message to an application running on the device, a servicerunning on the device, an operating system running on the device, aprocess running on the device, one or more applications running on aprocessor of the device, a software program running in the background ofthe device, or to one or more services running on the device.

The presently disclosed subject matter may further comprise, responsiveto a selection of a graphical element, sending a message requesting adata relating to a graphical element identified in an image from anapplication running on the external device, a service running on theexternal device, an operating system running on the external device, aprocess running on the external device, one or more applications runningon a processor of the external device, a software program running in thebackground of the external device, or to one or more services running onthe external device.

The presently disclosed subject matter may further comprise, responsiveto a selection of a graphical element, sending a message requesting adata relating to a graphical element identified in an image from anapplication running on the device, a service running on the device, anoperating system running on the device, a process running on the device,one or more applications running on a processor of the device, asoftware program running in the background of the device, or to one ormore services running on the device.

The message to the external device or website may be a command. Thecommand may be selected for example, from a command to run anapplication on the external device or website, a command to stop anapplication running on the external device or website, a command toactivate a service running on the external device or website, a commandto stop a service running on the external device or website, or acommand to send data relating to a graphical element identified in animage.

The message to the device may be a command. The command may be selectedfor example, from a command to run an application on the device, acommand to stop an application running on the device or website, acommand to activate a service running on the device, a command to stop aservice running on the device, or a command to send data relating to agraphical element identified in an image.

The presently disclosed subject matter may further comprise, responsiveto a selection of a graphical element, receiving from the externaldevice or website data relating to a graphical element identified in animage and presenting the received data to a user. The communication withthe external device or website may be over a communication network.

Commands and/or messages executed by pointing with two hands can includefor example selecting an area, zooming in or out of the selected area bymoving the fingertips away from or towards each other, rotation of theselected area by a rotational movement of the fingertips. A commandand/or message executed by pointing with two fingers can also includecreating an interaction between two objects such as combining a musictrack with a video track or for a gaming interaction such as selectingan object by pointing with one finger, and setting the direction of itsmovement by pointing to a location on the display with another finger.

According to the presently disclosed subject matter commands and/ormessages can be executed responsive to a predefined gesture which isbeing performed by the user during performing a pointing gesture beforeand/or after the aimed point is to identified. System 2 can beconfigured to detect a given gesture and execute an associated commandand/or message. Wherein gestures include, but are not limited to: aswiping motion, a pinching motion of two fingers, pointing, a left toright gesture, a right to left gesture, an upwards gesture, a downwardsgesture, a pushing gesture, opening a clenched fist, opening a clenchedfirst and moving towards the image sensor, a tapping gesture, a wavinggesture, a clapping gesture, a reverse clapping gesture, closing a handinto a fist, a pinching gesture, a reverse pinching gesture, a gestureof splaying fingers on a hand, a reverse gesture of splaying fingers ona hand, pointing at an graphical element, holding an activating objectfor a predefined amount of time, clicking on an graphical element,double clicking on an graphical element, clicking from the right side onan graphical element, clicking from the left side on an graphicalelement, clicking from the bottom on an graphical element, clicking fromthe top on an graphical element, grasping a graphical element of theobject, gesturing towards a graphical element of the object from theright, gesturing towards a graphical element from the left, passingthrough a graphical element from the left, pushing the object, clapping,waving over a graphical element, performing a blast gesture, performinga tapping gesture, performing a clockwise or counter clockwise gestureover a graphical element, grasping a graphical element with two fingers,performing a click-drag-release motion, and sliding an icon.

FIG. 2b is a functional block diagram illustrating an example of system2, in accordance with the presently disclosed subject matter. Asexplained above, processing unit 12 is operatively connected to imagesensor 8 and device 6 and comprises a processor 15 and computer memory13.

According to the example illustrated with reference to FIG. 2bprocessing unit further comprises images date-repository 202 configuredfor storing images captured by the image sensor; Graphical elementgenerator 204 configured to generate and display graphical elements onthe display; command execution module 206 configured to enable executionof a command associated with a respective icon displayed on the display;calibration module 208 configured for performing a calibration processas described below; and machine vision unit 210. Machine vision unit cancomprise for example gesture recognition module 212 configured toidentify in the captured images gestures made by the user; and viewingray determination module 214 configured to identify a point or an area(the aimed point) on the display towards which a user is pointing.

It is noted that the term “aimed point” should be broadly interpreted toinclude any point or area identified on the plane (e.g. display). Theaimed point can be defined for example as coordinates of one or morepoints (e.g. pixels) on the plane as well as an area on the plane.

Operations performed by the different functional components of system 2and more specifically of processing unit 12 are described in more detailbelow with reference to FIGS. 3-12. Operations described with referenceto FIGS. 3-12 are applicable in a system equipped with one or more imagesensors generating at least one of 2D images and 3D images.

FIG. 3 is a flowchart showing an example of operations which are carriedout in accordance with the presently disclosed subject matter. Theoperations described with reference to FIG. 3 can be performed forexample by system 2 described above.

At block 301 a image sensor situated adjacent to a display (6) capturesimages of the viewing space in front of the display. Images can becaptured and stored in a data-repository (e.g. image data-repository202) to be processed at a later stage. Alternatively, each image whichis captured can be processed immediately after it has been capturedwithout storing the image itself. The captured images can include forexample, a user positioned in front of the image sensor and attemptingto interact with one or more graphical elements displayed on a plane(e.g. by attempting to point towards an icon or text displayed on thedisplay).

One or more predefined body parts of the user (for example parts of theuser's face such as the user's eyes) and one or more pointing elementsare identified in the captured images (block 303). Once identified, dataindicative of the location of the one or more predefined body parts anddata indicative of the location of the one or more pointing elements isobtained. Identification of the user's body part and the pointingelements and obtaining of the respective location data can beaccomplished for example, with the help of machine vision unit 210 (forexample with the help of gesture recognition module 212).

A point on the display towards which the user is pointing (i.e. theaimed point) is to identified (block 305). The aimed point can beidentified for example with the help of viewing ray identificationmodule 214. As mentioned above, the user's eye 22, the pointing elementand the aimed point are collinear, lying on a common viewing ray 24.Thus, according to the presently disclosed subject matter processingunit 12 is configured to identify a viewing ray extending from apredefined body part of the user (e.g. the user's eye) through thepointing element and intersecting the display at a certain point i.e.the aimed point.

It is noted that the user's eye (or eyes) is one non-limiting example ofa facial part of the user which can be used for identifying a viewingray as disclosed herein and other facial parts (such as nose, ears, lipsetc.) and body parts can be similarly identified and used for thatpurpose. It should be further noted that wherever the eye of the user ismentioned in the present description it should be considered as anexample only and be broadly interpreted to include other parts of theface or body as well.

A graphical element displayed on the display which fulfills somepredefined criterion with respect to the identified location of theaimed point on the display (e.g. graphical element located closest tothe identified aimed point on the display) is determined as a graphicalelement selected by the user (block 307).

As described below according to the presently disclosed subject matteroperations associated with block 305 can further include one or moreprocesses designated for enhancing the identification of the point onthe display towards which the user is pointing.

Once a selected graphical element is determined, it is furtherdetermined whether a predefined condition is met while the pointingelement is pointing towards the selected graphical element (block 309).As mentioned above, the condition can be for example, a predefinedperiod of time during which the pointing element is pointing towards thedetermined point and/or a predefined gesture (e.g. a tapping motiontowards the display), or any other suitable condition. As furthermentioned above, once the predefined condition is met a command and/ormessage associated with the selected graphical element is executed(block 311). According to one example, command execution module 206 canbe configured to execute a command (e.g. by interacting with otherfunctional elements in device 6 or in some other device) which isassociated with the selected graphical element.

In view of the foregoing, it is understood that in order to determinewhich graphical element is selected by an interacting user it isrequired first to identify a location of a point on the display towardswhich the user is pointing. To this end, system 2 can be configured toobtain from one or more captured images, data indicative of the locationof one or more predefined body parts (e.g. user's eye) and one or morepointing elements within the viewing space, as viewed by the imagesensor. A viewing ray which correlates with the data indicative of thelocation of the one or more predefined body parts and the location ofthe one or more pointing elements can then be determined. For examplethe viewing ray can be extended through a first point representing thelocation of the one or more body parts and a second point representingthe location of the one or more pointing elements. The aimed point canbe determined at the intersection of the viewing ray with the plane.

In case system 2 comprises a 3D image sensor or a of pair 2Dstereoscopic image sensors, processing unit 12 can be configured tolocate the (X,Y,Z) location of the user's eye 22 and/or the user'sfingertip 14 in the 3D viewing space. The processing unit thendetermines a viewing ray 24 having a vertex at the eye 22 and passingthrough the fingertip 14. As illustrated in FIG. 1, dot 18 is thenpositioned on the display 6 where the viewing ray intersects thedisplay.

In some cases system 2 can comprise a combination of 2D image sensor(generating 2D image information) and 3D image sensor (generating 3Dimage information) and be configured to obtain from images captured bythe 2D image sensor information regarding the X,Y coordinates of theuser's eye 22 and the user's fingertip 14 and obtain from imagescaptures by the 3D image sensor, information regarding the z coordinateof the user's eye 22 and the user's fingertip 14. The combinedinformation from the 2D and 3D image sensors can be used for determiningthe 3 dimensional viewing ray. For example, the 3D image sensor can becharacterized by a resolution which is lower than the resolution of the2D image sensor (e.g. the resolution of the depth sensor is less than aquarter of the resolution of the 2D image sensor).

A greater challenge is tackled when using a 2D image sensor. A userstanding in front of a display can point anywhere on the display and thespecific viewing ray by which the user is pointing can be determinedbased on the 2D position (e.g. X,Y coordinates) of the eyes of the userand the 2D position of the pointing element as captured by the imagesensor along with the distance of the user or user's eyes from thedisplay and the distance of the pointing element (e.g. the user'sfingertip) from the display or the user's body.

According to the presently disclosed subject matter processing unit 12can be configured to determine a point on the display towards which theuser is pointing (aimed point) as follows. The X,Y coordinates of theuser's eyes (or some other one or more predefined body parts) can beidentified in images captured by the image sensor and the distance ofthe user from the display (R1) can be estimated. Based on the estimateddistance R1 the z coordinate of the user's eyes in the viewing space canbe obtained.

R1 can be determined for example, based on the distance between theuser's eyes as identified in an image obtained by the image sensor.Similarity exists between the distances between the eyes (e.g. pupils)of different individuals. Higher similarity may be found betweenindividuals of the same ethnic group. Therefore the distance between theeyes of a user can be indicative of the distance of the eyes from thedisplay.

In addition, the X,Y coordinates of the pointing element can beidentified in images captured by the image sensor. Using the estimateddistance of the pointing element from the user's body (in the directionof the display referred below as R2), the z coordinate of the pointingelement in the viewing space can be obtained. Methods of estimating thedistance of the pointing element from the user's body are discussedbelow.

Once the X,Y,Z coordinates of the user's eyes and the X,Y,Z coordinatesof the pointing element are obtained, a straight line (viewing ray)extending through these two points is determined and the point wherethis line intersects the display is identified. The identified point ofintersection of the line with the display is determined as the point onthe display towards which the user is pointing (the aimed point).

In case the display is 3D display the displayed graphical elements canbe 3D graphical elements and can be perceived to the user as beinglocated in the viewing space located in front of the display or behindthe display. Thus, determination of an aimed point can be performed bydetermining a viewing ray extending from the user's eyes, through thepointing element and through the first graphical element (e.g. a 3Dgraphical element) intersecting the viewing ray.

As described above, in order to determine the point on the displaytowards which a user is pointing, it is required to identify thelocation of the pointing element in the viewing space while pointing.Therefore it is required to identify the location of the pointingelement during a pointing gesture where the pointing element is assumedto be pointing towards a selected point on the display. The pointingelement location (referred herein as point P′), which could be forexample the point where the pointing element is located closest to thedisplay point P′. FIG. 4 is a schematic illustration demonstrating pointP′ during a pointing gesture, in accordance with the presently disclosedsubject matter.

As used herein the term “pointing gesture” refers to a gestured of apointing element, aimed to point to a desired area or point on adisplay. For example, a pointing gesture may be a gesture performed by auser in which his fingertip is moved in space in front of a displaytowards a certain graphical element displayed on the display. During thepointing gesture in at least a portion of the motion of the pointinggesture the pointing element is extended towards a desired point on thedisplay. In FIG. 4 the motion path of the pointing element during apointing gestures is indicated as line PG comprising point P′ locatedclosets to the display.

According to the presently disclosed subject matter system 2 can beconfigured to identify, during a pointing gesture, point P′ where thepointing element is located closest to the display.

If a depth image sensor or a stereoscopic image sensors are used,processing unit 12 can be configured to extract point P′ from a capturedframe where the Z coordinate of point P′ is determined where thepointing element is located closest to the display. For example, if theimage sensor is located on the same plane as the display, the coordinateof the P′ is where the Z coordinate is the smallest.

When using a single 2D image sensor, point P′ can be identified based onthe analysis of one or more features of the pointing element during thepointing gesture including for example: a collection of all or part ofposition data components of the pointing element during the pointinggestures, the motion path of the pointing element during the pointinggesture, the motion vectors of the pointing element, the change inmotion vectors of the pointing element, relation between differentmotion vectors, the pose (or the change in the pose) of the pointingelement in space during the pointing gesture, the size of the pointingelement, and acceleration and deceleration of the pointing elementduring the pointing gesture.

After point P′ is reached, the user retracts his arm. Changes in theposition of the pointing element in the viewing space (e.g. as indicatedby coordinates), which indicate that the arm has been retracted, can beidentified and used to identify the location of point P′.

According to another example the location of point P′ can be identifiedbased on changes in the size of the pointing element during the pointinggesture. As the user extends his arm closer towards the display, thesize of the pointing element increases (e.g. the size of the user'sfingertip in the captured images is increased). Processing unit 12 canbe configured to track the size of the pointing element and determinethe location of the pointing element where the size of the pointingelement (or more specifically the tip of the pointing element) is thelargest.

FIG. 5 is a flowchart illustrating an example of operations performedfor identifying point P′, in accordance with the presently disclosedsubject matter. Operations described with reference to FIG. 5 can beexecuted for example, by processing unit 12 described above (e.g. withthe help of machine vision module 210).

The image sensor captures images of the user while attempting tointeract with graphical elements displayed on the display (block 501). Apointing element is identified in the captured images (block 503). Thecaptured images are processed and changes in the size of the pointingelement in different images are identified (block 505).

For example, the ratio between the size of the fingertip at the initialposition, at the start of the pointing gesture, and the size of thefingertip along different positions along the motion of the arm towardsthe display can be calculated and the percentage of growth in size ofthe fingertip can be identified. Once the pointing element is at theshortest distance from the display the greatest change in its size isidentified. When the arm is then retracted the change in size isreversed as the size of the tip becomes smaller.

A position of the pointing element where the greatest change isidentified between the initial and current size of the tip of pointingobject is identified (block 507). This position is designated as pointP′ (block 508).

As mentioned above the distance of the user's eyes from the display (R1)and the distance of the pointing element from the user's body areestimated in order to identify a point on the display towards which theuser is pointing.

FIG. 6a is a schematic illustration showing a top view of a userpointing towards a display, in accordance with the presently disclosedsubject matter. FIG. 6a shows image sensor 8 positioned adjacent todisplay 6 capable of capturing images of a three-dimensional viewingspace indicated by the broken lines 10. The distance of the user fromthe display is indicated by line R1 extending from the display to apoint on an imaginary line between the eyes (e.g. between the pupils) ofthe user. As mentioned above distance R1 can be determined for example,based on the distance between the user's eyes as identified in an imageobtained by the image sensor.

Furthermore, based on typical human behavior it can be assumed that whena user is pointing towards the display his arm is not fully extendedfrom his body, and neither is it fully retracted towards the body. Thelength of the extension of the pointing element from a predefined bodypart of the user (e.g. the user's eye) towards the display is indicatedin FIG. 6a by range R2.

R2 can be estimated, for example, based on the user's height and theestimated proportions of his body and possibly also on informationindicating the distance of the user from display (R1). Additionally,information with respect to the age and gender of the user can be alsoused during the estimation of R2.

In addition, R2 can be optionally estimated based on recordedstatistical information which is obtained from a plurality of users andindicates the length of the extension of the arm towards the display ofthe users while pointing (e g taking into consideration the height andproportions of each user). Optionally this information can be classifiedbased on geographical and/or ethnic origin of the users, in order todiscriminate between different pointing gestures which may be typical todifferent geographical and/or ethnic origins. Thus, for example, anaverage length of R2 can be calculated based on the recorded informationwith respect to the extension of the arm of many users.

While R2 can enable to estimate the distance of the pointing elementfrom the user's body, some deviation may still exist between theextensions of the arm in the pointing gestures made by different users.FIG. 6a further illustrates Ar which is another range representing thepossible deviation in the extension of the arm between differentpointing gestures. Assuming that, as mentioned above, R2 is an averagevalue of the measured extension of the arm in pointing gestures ofdifferent users, Ar can be determined, for example, as a value whichequals to one or more standard deviations of that average valuedescribed above (e.g. after normalization of the height factor).

Unlike a 3D image sensor, the images which are captured by a 2D imagesensor provide a projecting of the image of the user onto the displaywithout real depth perception. FIG. 6b is a schematic illustrationshowing different extensions of a pointing element generating a similarprojection in accordance with the presently disclosed subject matter.FIG. 6b shows image sensor 8 positioned adjacent to display 6 capable ofcapturing images of a three-dimensional viewing space. Images of user 45are captured by image sensor 8. User 45 is extending his arm andpointing at display 6. Two extensions of different lengths are shown.The viewing ray extending from extension ‘a’ (the longer extension)intersects display 6 at point 1 while the viewing ray extending fromextension ‘b’ (the shorter extension) intersects display 6 at point 2.As illustrated in FIG. 6b , although extensions ‘a’ and ‘b’ are pointingto different points on the display they are both viewed by image sensor8 in the same manner—converging on the same line R3.

As mentioned above, in order to identify a point on the display towardswhich a user is pointing, a viewing ray connecting the eyes of the user,the pointing element and a respective point of intersection of theviewing ray with the display, is determined. However, as a result ofvarious uncertainties which exist during the identification of theviewing ray, uncertainly also exists as to where exactly on the displaythe user is pointing.

The uncertainties include for example, uncertainty with regard to theidentification of the tip of the pointing object, and identification ofa point located between the eyes, which best represents the viewing ray.Furthermore, as explained to above, in case 2D image sensor is used, anadditional uncertainty results from the ambiguity with respect to theactual extension of the pointing element from the body of the user andwith respect to the distance of the user from the display.

As a result of these uncertainties, when a user is pointing towards thedisplay, instead of identifying a single point on the display towardswhich the user is pointing, a larger plane can be identified on thedisplay (referred to herein as a “candidate plane”). The candidate planerepresents a plane on which a plurality of possible lines extending fromthe eyes of the user through the pointing element intersect the display.An image obtained by image sensor 8 will include the user's eye and thefingertip 14, and will thus include a projection of the viewing ray ontothe projection plane (the projection plane being the plane captured bythe image sensor). The set of all lines in the viewing space whoseprojection onto the projection plane is the same as the projection ofthe viewing ray onto the projection plane form a plane, referred toherein as the “candidate plane”. Each line extending from the user's eyethrough a pointing element and a common candidate plane is referred toherein as a “candidate viewing ray”. A candidate plane can becharacterized by different features including for example, the number ofpixels in a candidate plane (a candidate plane can comprise one or morepixels), its size (e.g. in pixels or its measured diameter), its shape,its location on the screen, etc.

Accordingly, it would be advantageous to more accurately identify apoint or area on the display towards which a user is pointing,notwithstanding the uncertainties mentioned above.

One possible solution to this problem, which is provided herein, isbased on a calibration process. In the calibration process, the user isinstructed to point sequentially at each of one or more graphicalelements (e.g. icons) displayed on the display. One of the graphicalelements can be for example a graphical element whose selection isrequired to switch the device from standby mode to active mode or unlockthe display. When a user points towards such a graphical element, theprocessing unit 12 determines the position of the pointing element andthe user's eyes in an image obtained by the image sensor system whilethe user is pointing at the graphical element. The user's fingertip maybe identified in an image obtained by the image sensor, for example, asdisclosed in Applicant's co-pending U.S. patent application Ser. No.10/593,628 having publication number 2008-0042981. Methods foridentifying a face and eyes in an image are well known in the art. Whenthe user subsequently points to an icon on the display, the processingunit 12 determines the point on the display, and hence the icon, towhich the user is pointing using the calibration data, together withlimitations on the distance between the user's eye 22 and fingertip 14and the distance of the user from the display 6 which may be determinedfrom the distance between the user's eyes in the image obtained by theimage sensor.

FIG. 7 is a flowchart illustrating operations performed during acalibration process, in accordance with the presently disclosed subjectmatter. Operations described with reference to FIG. 7 can be executed byprocessing unit 12 described above (e.g. with the help of calibrationmodule 208).

During the calibration process the location of one or more predefinedbody parts of the user (e.g. the user's eyes), the location of thepointing element within the viewing space, and the distance of thepointing element from the user body when reaching point P′ are moreaccurately estimated. At block 701 one or more graphical elements (e.g.icons) are displayed on the display. The graphical elements aredisplayed on the display in a predefined location, order or shape andprovide a calibration sequence. The calibration sequence ischaracterized by the location of graphical elements on the display andthe time and/or sequence of interaction with the different graphicalelements. The user is required to interact (e.g. point to or swipe) withthe graphical elements according to a predefined order. Alternatively oradditionally, a calibration sequence can include a graphical elementthat should be swiped or moved according to a predefined pattern orshape.

More accurate estimation of the location of one or more predefined bodyparts of the user (e.g. the user's eyes) and the location of thepointing element within the viewing space is performed by using theinformation of the known location toward which the user is pointing,e.g. a graphical element which is displayed in a predefined location.

In some cases the user may be unaware of the calibration process. Forexample, as mentioned above, the calibration process can be presented tothe user as an interaction required for unlocking the display (e.g.swiping a graphical element displayed on the display from left toright).

The user interacts with the display as required by the calibrationsequence and the image sensor captures images of the user while doing so(block 703). The 2D location (e.g. in X,Y coordinates) of the user (e.g.the user's eyes) in the image obtained by the image sensor is determined(block 705). A pointing gesture is identified and a Point P′ isdetermined e.g. using the location of the pointing element (e.g. in X,Ycoordinates) where the pointing element is located closest to thedisplay (block 707).

Since the calibration process is executed in accordance with apredefined calibration sequence, information indicating on which of thegraphical elements displayed on the display, the user is currentlysupposed to be pointing, is available to processing unit 12. Therefore,the processing unit can more easily correlate between a viewing rayconnecting the location of the user, point P′ and a respective graphicalelement on the display, towards which the user is pointing. Accordingly,a respective viewing ray is extended from the relevant graphical elementon the display, through the pointing element located at the respectivepoint P′ and on to the respective location of the user's body part (e.g.user's eyes) (block 709).

Feedback can be provided to the user (e.g. by changing one or more ofthe color, size, shape and position of the respective graphical elementor by an audible indication). As the user follows the calibrationsequence and interacts with the respective graphical elements on thedisplay, the operations described with reference to blocks 703 to 709may be repeated (block 711).

FIG. 8 is a schematic illustration demonstrating one example of thecalibration process. FIG. 8 shows image sensor 8 positioned adjacent todisplay 6 capable of capturing images of a three-dimensional viewingspace indicated by the broken lines 10. A user is pointing towards iconG₁, which is displayed on the display as part of a calibration sequence(not shown). The user's eyes are in the 3D space in front of the imagesensor, located along line L1. The pointing element location at point P′in the 3D space in front of the image sensor is located along line L2.

The distance of the user from the display (R1) can be estimated asdescribed above; however, the calibration process enables to improvethis estimation. Similarly the range R2 can be estimated as mentionedabove; however, the calibration process enables to improve thisestimation.

As described above with reference to FIG. 6a uncertainty exists withregard to the estimated range R2 (indicated above by Ar). According toone example, during the calibration process a first straight line (L3)is extended from icon G₁ on the display such that by crossing line L2and line L1 the distance R2′ is equal to R2-Ar and a second straightline (L4) is extended from icon G₁ on the display such that by crossingline L2 and line L1 the distance R2″ equals R2+Δr.

A point EL₁ on line L1 representing the estimated location of the usercan be determined as any point located between u1 and u2. For example,it can be the point located exactly at the middle between the twopoints. A respective point PL_(i) on line L2 can be determined byextending a straight line from point EL to icon G₁. R2 can be estimatedas distance R2′″. For any icon G_(i) a respective point EL_(i)representing the location of the user's eyes; and a point PL_(i)representing the location of the pointing element can be determined asdescribed above.

Reverting to FIG. 7, at block 713 the calibration estimation of range R1and range R2 is determined. The calibration estimation of range R1 canbe determined using on all the collected points EL obtained with respectto the different icons in the calibration sequence (e.g. a point locatedat the center of all identified points). The calibration estimation ofrange R2 can be determined using on all the collected distances R′″obtained with respect to the different icons in the calibrationsequence, each related to a respective EL_(i).

Once the system is calibrated, during regular operation, in response toa pointing gesture of the user towards the display, the point on thedisplay towards which the user is pointing can be determined using thevalues of R1 and R2 as estimated in the calibration process (block 715).

According to the presently disclosed subject matter, processing unit 12can be configured to determine a different range R2 for each icon on thedisplay and create a calibration map associating the different icons andtheir respective location on the display with a corresponding range R2.Any other point on the display (not populated by a calibration icon),can be associated with respective range R2 based on the calibration map.This association can be based for example, on a linear combination ofthe location of icons and their respective range R2.

During regular operation, processing unit 12 can be configured,responsive to a pointing gesture of a user towards the display, toidentify the general direction of the pointing gesture, and select aspecific range R2 which is associated to a calibration icon located at apoint on the display which is closest to the identified generaldirection.

In addition to or instead of the calibration process described above,the presently disclosed subject matter provides other techniques whichenable to improve accuracy of identification of a point or area on thedisplay towards which the user is pointing. As explained above, due todifferent uncertainties related to parameters used when determining apoint on the display towards which the user is pointing, a candidateplane is identified on the display which represents a plane on which aplurality of possible lines extending from the eyes of the user throughthe pointing element intersect with the display.

The presently disclosed subject includes a technique for reducing thesize of the candidate plane, and more accurately identifying the pointon the display towards which the user is pointing.

In general, a first type of features and a second type of features canbe obtained from captured images of a user interacting with the plane.The first type of features includes features with respect to the motionpath of the pointing element during a pointing gesture made by a user.The first type of features include for example, a collection of all orpart of the position data components of the pointing element during thepointing gestures, the motion path of the pointing element during thepointing gesture, the motion vectors of the pointing element, the changein motion vectors of the pointing element, relation between differentmotion vectors, the pose (or the change in the pose) of the pointingelement in space during the pointing gesture, the size of the pointingelement, and acceleration and deceleration of the pointing elementduring the pointing gesture.

The second type of features includes features with respect to the one ormore candidate planes identified on the plane. The second type offeatures includes for example, size of the candidate planes, location ofcandidate planes on the plane, shape of the candidate plane, overlapbetween different candidate planes.

The processing unit can be configured to determine the aimed point onthe plane using at least one of the first type of features, and thesecond type of features.

FIG. 9 is a flowchart illustrating an example of operations performedfor reducing the size of the candidate plane, in accordance with thepresently disclosed subject matter. Operations described with referenceto FIG. 9 can be executed for example, using processing unit 12described above (e.g. with the help of machine vision unit 210).

At block 901, the image sensor captures images of the user whileattempting to interact with graphical elements displayed on the display.The captured images are processed and the user's eyes and a pointingelement are identified in the captured images (block 903). The motionpath of the pointing element while it is being extended towards thedisplay is traced and a sequence of position data components comprisingdifferent positions of the pointing element (e.g. user's fingertip) inthe motion path is obtained (block 905).

The position data components are features, which are related to thefirst type of features mentioned above. More specifically, the positiondata components are features that describe the position of a pointingelement in a given frame. For example, position data components caninclude X,Y coordinates of the tip of the pointing element in theviewing plane captured by the image sensor. According to this example,while the user's ara is extended closer towards the display, the twodimensional position of his fingertip with respect to the viewing plane(indicated by X,Y coordinates) at different points during the motion,can be obtained and stored. Each stored position point (e.g. x,ycoordinates) being a respective position data component.

According to the presently disclosed subject matter, the motion of thefingertip is traced until it is identified that the fingertip is locatedat point P′ (block 907). At this point two or more position datacomponents are selected from the sequence of position data componentsextracted from the motion path of the pointing element towards thedisplay. The selected position data components can be for example, theposition data components which correlate with the N frames before thepointing element reached point P′ (the closest point to the display).Alternatively, the selected position data components can be positionslocated on similar viewing rays. A pair of similar viewing rays can bedefined as viewing rays characterized by a distance which is smallerthan a predefined value at the portion of the viewing ray locatedbetween the user's eyes and the display.

As explained above, each position data component in the collection ofselected position components (represented for example, by X,Y,coordinates on the viewing plane) is associated with a respectiveviewing ray connecting, the user's eye through the pointing elementlocated at a position indicated by the respective position datacomponent, and intersecting the display. Due to the uncertaintiesdiscussed above, each of the viewing rays can be associated with arespective candidate plane on the display and not with one accuratepoint.

The respective candidate planes associated with the selected positiondata components are identified on the display (block 909). At block 911an overlapping region between the candidate planes is identified and isdesignated as a selected viewing plane representing the aimed point(note that the relative location of the different candidate planes andtheir respective surfaces are features related to the second type offeatures mentioned above). Thus, the size of the candidate plane isreduced and a smaller area on the display is identified as the aimedpoint.

FIG. 10 is a schematic illustration showing three partially overlappingcandidate planes, in accordance with the presently disclosed subjectmatter. Each candidate plane is illustrated as a circle covering acertain area on the display. For example, each plane is associated witha different position data component of the three last position datacomponents from the collection of selected position values as describedabove (position values: n, n−1 and n−2). As illustrated in FIG. 10 thethree candidate planes all point to the adjacent areas and share anoverlapping portion (area filled with short lines) which is designatedas the selected projection plane. An aim point may be determined as thecenter of the selected projection plane.

The presently disclosed subject matter further discloses anothertechnique which enables to more accurately identify the point on thedisplay towards which the user is pointing. FIG. 11 is a flowchartillustrating operations carried out, in accordance with the presentlydisclosed subject matter. Operations described with reference to FIG. 11can be executed by system 2, inter alia, with the help of processingunit 12 described above.

According to the subject matter disclosed herein, system 2 can beconfigured to provide feedback to a user pointing towards the display.This feedback assists the user to direct the pointing element towards adesired point on the display and therefore enables the user to moreeasily select a desired graphical element. As mentioned above thefollowing operations are provided in the context of a 2D display,however similar operations, mutatis mutandis, can be executed with a 3Ddisplay.

As before, the image sensor captures images of the user while attemptingto interact with graphical elements displayed on the display (block1101). The user's eyes and pointing elements are identified in thecaptured images obtained by the image sensor (block 1103). Responsive tothe detection of a pointing gesture, a pointing visual effect isdisplayed on the display (block 1105).

The pointing visual effect can be any kind of static or animatedgraphical element including for example: a smudge of color characterizedby any shape or color, can be transparent or opaque, can be presentedpartially or fully, can be on top of one or more graphical elementdisplayed on the display and/or behind of the same or other one or moregraphical elements displayed on the display.

For example, the pointing visual effect can have a round symmetricalshape and a transparent color through which the graphical elements arediscernible and can appear to the user as a flashlight beam illuminatinga portion of the display. The characteristic of pointing visual effect(such as, location, size, colors, shape, brightness, transparency level)may be changed during the time it is being displayed on the display.

In the case of 3D display, the pointing visual effect can be for examplean animation of an illuminating circle that starts at a certain distancefrom the display and becomes smaller as the pointing element is movingcloser to the display. Other examples of pointing visual effects includea graphical element (static or animated) that is perceived to the useras located on the pointing element at the beginning of the pointinggestures and which moves together with the pointing element as it ismoving closer to the display.

In the case of 3D display, the pointing visual effect may be perceivedin one or more locations which are perceived to the user as located atdifferent distances from the display.

Optionally system 2 can be configured to display different types ofpointing visual effects. System 2 can be configured to allow a user toselect (configure) which type or types of pointing visual effect ispreferred. Alternatively or additionally, the selection (configuration)of desired pointing visual effects can be controlled by an application.For example pointing visual effects can be adapted to the graphicalelements which are being displayed on the display.

According to one example, the pointing visual effect can be displayed onthe display when a predefined pointing visual effect condition is met.The predefined pointing visual effect conditions can be related to theposition of the pointing element in the viewing space, including forexample, an estimated distance of the pointing element from the user'seyes, and a change in size of the pointing element. Alternatively oradditionally, the predefined pointing visual effect conditions can berelated to the motion path of the pointing element, including the timethat has passed from the beginning of the pointing gesture, motionvectors values (e.g. position data components), detected changes in thespeed of the pointing gesture along the motion path, decelerate of thepointing element along the motion path, estimated time until thepointing element is bound to reach point r.

During the pointing gesture, for each location of the pointing elementin the viewing space there is a respective point of intersection of aviewing ray with the plane. Thus, according to another example, thepredefined pointing visual effect conditions may be related to thedistribution of the intersection points on the plane (e.g. the pointingvisual effect condition can be that the distance between theintersection points is less than a predefined value). In anotherexample, the initial location of the pointing visual effect on thedisplay can be determined based on the initial pointing direction of thepointing element.

During the pointing gesture, the motion path of the pointing elementtowards the display is traced (block 1107). While tracing the pointingelement a respective sequence of position data components can beobtained as described above with reference to block 905 in FIG. 9.

As the pointing element is moving closer towards the display, one ormore characteristics of the pointing visual effect are altered incorrelation to the movement of the pointing element (block 1009). Thecharacteristics can include for example, the location, shape, size,color, brightness and transparency level of the pointing visual effector any other characteristic. For instance, the pointing visual effectcan diminish in size as the distance between the pointing element andthe display shortens.

As the user extends his arm towards the display, he intuitively attemptsto move the pointing visual effect towards the position of a desiredgraphical element displayed on the display. The processing unit isconfigured to identify the rectifying movements of the pointing elementwhich are made by the user, in attempt to move the pointing visualeffect towards the selected graphical element. Optionally, theprocessing unit can be configured to change the position of the pointingvisual effect on the display based on the identified rectifying movementof the pointing element performed by the user. For example, the positionof the pointing visual effect on the display can change in correlationto the direction of the rectifying gestures which are made by the user.

In another example, a circular pointing visual effect becomes smaller asthe pointing element is moving closer towards the display. Optionallythe pointing visual effect can shrink in the direction of the rectifyinggesture. FIG. 12a illustrates a pointing visual effect which is shrunkin size and migrates to the left, responsive to a rectifying gesturetowards an icon (indicated by a square) located on the left and FIG. 12billustrates a pointing visual effect which is shrunk in size andmigrates to the right, responsive to a rectifying gesture towards anicon (indicated by the square), located on the right.

Using the known position of the pointing visual effect on the displayand possibly also on the direction of the movement of pointing element,a graphical element such as an icon which complies with a predefinedcriterion with respect to the pointing visual effect, can be identifiedand determined as a selected icon (block 1013). For example, an iconwhich is located closest to the pointing visual effect or which islocated relative to the pointing visual effect in the direction of therectifying gesture, can be determined as the icon selected by the user.

It will also be understood that the system according to the presentlydisclosed subject matter may be a suitably programmed computer.Likewise, the presently disclosed subject matter contemplates a computerprogram being readable by a computer for executing the method of thepresently disclosed subject matter. The presently disclosed subjectmatter further contemplates a machine-readable memory tangibly embodyinga program of instructions executable by the machine for executing themethod of the presently disclosed subject matter.

It is to be understood that the presently disclosed subject matter isnot limited in its application to the details set forth in thedescription contained herein or illustrated in the drawings. Thepresently disclosed subject matter is capable of other embodiments andof being practiced and carried out in various ways. Hence, it is to beunderstood that the phraseology and terminology employed herein are forthe purpose of description and should not be regarded as limiting. Assuch, those skilled in the art will appreciate that the conception uponwhich this disclosure is based may readily be utilized as a basis fordesigning other structures, methods, and systems for carrying out theseveral purposes of the present presently disclosed subject matter.

1. A method of recognizing an aimed point on a plane the methodcomprising: obtaining at least one image of a viewing space of an imagesensor; processing the at least one image by at least one processoroperatively connected to the image sensor and obtaining data indicativeof location of at least one pointing element in the viewing space;obtaining data indicative of at least one predefined user's body part inthe viewing space; and determining by the at least one processor, apoint or area on the plane, using the data indicative of the location ofthe at least one pointing element, the data indicative of the locationof at least one predefined user's body part, thus yielding the aimedpoint on the plane; determining, while obtaining data indicative oflocation of at least one pointing element in the viewing space that apredefined condition is met; and executing a predefined command and/ormessage associated with the aimed point. 2-61. (canceled)